2 * Copyright (C) 2001-2002 Sistina Software (UK) Limited.
3 * Copyright (C) 2006-2008 Red Hat GmbH
5 * This file is released under the GPL.
8 #include "dm-exception-store.h"
10 #include <linux/ctype.h>
12 #include <linux/pagemap.h>
13 #include <linux/vmalloc.h>
14 #include <linux/slab.h>
16 #define DM_MSG_PREFIX "snapshot exception stores"
18 static LIST_HEAD(_exception_store_types
);
19 static DEFINE_SPINLOCK(_lock
);
21 static struct dm_exception_store_type
*__find_exception_store_type(const char *name
)
23 struct dm_exception_store_type
*type
;
25 list_for_each_entry(type
, &_exception_store_types
, list
)
26 if (!strcmp(name
, type
->name
))
32 static struct dm_exception_store_type
*_get_exception_store_type(const char *name
)
34 struct dm_exception_store_type
*type
;
38 type
= __find_exception_store_type(name
);
40 if (type
&& !try_module_get(type
->module
))
52 * Attempt to retrieve the dm_exception_store_type by name. If not already
53 * available, attempt to load the appropriate module.
55 * Exstore modules are named "dm-exstore-" followed by the 'type_name'.
56 * Modules may contain multiple types.
57 * This function will first try the module "dm-exstore-<type_name>",
58 * then truncate 'type_name' on the last '-' and try again.
60 * For example, if type_name was "clustered-shared", it would search
61 * 'dm-exstore-clustered-shared' then 'dm-exstore-clustered'.
63 * 'dm-exception-store-<type_name>' is too long of a name in my
64 * opinion, which is why I've chosen to have the files
65 * containing exception store implementations be 'dm-exstore-<type_name>'.
66 * If you want your module to be autoloaded, you will follow this
69 * Returns: dm_exception_store_type* on success, NULL on failure
71 static struct dm_exception_store_type
*get_type(const char *type_name
)
73 char *p
, *type_name_dup
;
74 struct dm_exception_store_type
*type
;
76 type
= _get_exception_store_type(type_name
);
80 type_name_dup
= kstrdup(type_name
, GFP_KERNEL
);
82 DMERR("No memory left to attempt load for \"%s\"", type_name
);
86 while (request_module("dm-exstore-%s", type_name_dup
) ||
87 !(type
= _get_exception_store_type(type_name
))) {
88 p
= strrchr(type_name_dup
, '-');
95 DMWARN("Module for exstore type \"%s\" not found.", type_name
);
102 static void put_type(struct dm_exception_store_type
*type
)
105 module_put(type
->module
);
109 int dm_exception_store_type_register(struct dm_exception_store_type
*type
)
114 if (!__find_exception_store_type(type
->name
))
115 list_add(&type
->list
, &_exception_store_types
);
122 EXPORT_SYMBOL(dm_exception_store_type_register
);
124 int dm_exception_store_type_unregister(struct dm_exception_store_type
*type
)
128 if (!__find_exception_store_type(type
->name
)) {
133 list_del(&type
->list
);
139 EXPORT_SYMBOL(dm_exception_store_type_unregister
);
142 * Round a number up to the nearest 'size' boundary. size must
145 static ulong
round_up(ulong n
, ulong size
)
148 return (n
+ size
) & ~size
;
151 static int set_chunk_size(struct dm_exception_store
*store
,
152 const char *chunk_size_arg
, char **error
)
154 unsigned long chunk_size_ulong
;
157 chunk_size_ulong
= simple_strtoul(chunk_size_arg
, &value
, 10);
158 if (*chunk_size_arg
== '\0' || *value
!= '\0') {
159 *error
= "Invalid chunk size";
163 if (!chunk_size_ulong
) {
164 store
->chunk_size
= store
->chunk_mask
= store
->chunk_shift
= 0;
169 * Chunk size must be multiple of page size. Silently
170 * round up if it's not.
172 chunk_size_ulong
= round_up(chunk_size_ulong
, PAGE_SIZE
>> 9);
174 /* Check chunk_size is a power of 2 */
175 if (!is_power_of_2(chunk_size_ulong
)) {
176 *error
= "Chunk size is not a power of 2";
180 /* Validate the chunk size against the device block size */
181 if (chunk_size_ulong
% (bdev_hardsect_size(store
->cow
->bdev
) >> 9)) {
182 *error
= "Chunk size is not a multiple of device blocksize";
186 store
->chunk_size
= chunk_size_ulong
;
187 store
->chunk_mask
= chunk_size_ulong
- 1;
188 store
->chunk_shift
= ffs(chunk_size_ulong
) - 1;
193 int dm_exception_store_create(struct dm_target
*ti
, int argc
, char **argv
,
195 struct dm_exception_store
**store
)
198 struct dm_exception_store_type
*type
;
199 struct dm_exception_store
*tmp_store
;
203 ti
->error
= "Insufficient exception store arguments";
207 tmp_store
= kmalloc(sizeof(*tmp_store
), GFP_KERNEL
);
209 ti
->error
= "Exception store allocation failed";
213 persistent
= toupper(*argv
[1]);
214 if (persistent
!= 'P' && persistent
!= 'N') {
215 ti
->error
= "Persistent flag is not P or N";
219 type
= get_type(&persistent
);
221 ti
->error
= "Exception store type not recognised";
226 tmp_store
->type
= type
;
229 r
= dm_get_device(ti
, argv
[0], 0, 0,
230 FMODE_READ
| FMODE_WRITE
, &tmp_store
->cow
);
232 ti
->error
= "Cannot get COW device";
236 r
= set_chunk_size(tmp_store
, argv
[2], &ti
->error
);
240 r
= type
->ctr(tmp_store
, 0, NULL
);
242 ti
->error
= "Exception store type constructor failed";
251 dm_put_device(ti
, tmp_store
->cow
);
258 EXPORT_SYMBOL(dm_exception_store_create
);
260 void dm_exception_store_destroy(struct dm_exception_store
*store
)
262 store
->type
->dtr(store
);
263 dm_put_device(store
->ti
, store
->cow
);
264 put_type(store
->type
);
267 EXPORT_SYMBOL(dm_exception_store_destroy
);
269 int dm_exception_store_init(void)
273 r
= dm_transient_snapshot_init();
275 DMERR("Unable to register transient exception store type.");
279 r
= dm_persistent_snapshot_init();
281 DMERR("Unable to register persistent exception store type");
282 goto persistent_fail
;
288 dm_persistent_snapshot_exit();
293 void dm_exception_store_exit(void)
295 dm_persistent_snapshot_exit();
296 dm_transient_snapshot_exit();